Performance of Tangential Injection on Starting Characteristics of Hypersonic Inlet

The hypersonic inlet has poor starting ability under low Mach number conditions, which limits its available range of Mach number. Aiming at the phenomenon that the inlet of a Rocketed Based Combined Cycle (RBCC) engine does not start at a low Mach number, a tangential jet scheme with nozzles was designed, and the two-dimensional flow field of the inlet was analyzed. Numerical simulations show the changes pattern of jet parameters under different nozzle configurations and boundary conditions. The effect of tangential jets on the starting performance of hypersonic inlets is studied and it is found that tangential jets can effectively reduce the starting Mach number of the inlets. Under the interference of the tangential jet, the flow field of the inlet is significantly changed, and the flow coefficient, the total pressure recovery coefficient, and the anti-backpressure ability are significantly improved. It is also found that the jet parameter that affects the starting performance of the inlet is not the jet flow momentum but the jet flow kinetic energy. When the jet flow kinetic energy is greater than a certain threshold, the inlet can be successfully started at a low Mach number.